Modern digital cameras may provide the capability of capturing multiple focal stack images. Each of the focal stack images may focus on a different focus plane. The focus information allows segmentation of the foreground and background of the focal stack images.
Conventionally, a focus measure is calculated for each pixel, classifying each sharp pixel as foreground and each blurry pixel as background. However the per pixel focus measurement is not always reliable, especially in areas with depth discontinuity and texture weak areas. Further, the segmentation calculations are inefficient when using sophisticated segmentation techniques. For example, if graph-cut algorithm is used, each pixel will form a node on the graph, making the graph extremely large resulting in long computation time.
There is a lack of balance between incorporating user input into the segmentation calculations and minimizing user burden. User input is either not used in the calculations, or the user input requires significant detail and is burdensome to the user.